introductory word commas

Front

In the following sentence, where does the comma belong?
Oh that is very interesting!

Back

After: Oh

Front

Where should the comma be placed? Wow I didn't know you were from Jamaica.

Back

Wow, I didn't know you were from Jamaica

Front

In the following sentence, where does the comma belong? Yes you can have my pizza and wings.

Back

Yes, you can have my pizza and wings.

Front

Where should the comma be placed? Yes while I was doing my homework I stumbled against some unknown words.

Back

Yes, while I was doing my homework I stumbled against some unknown words.

Front

what does a comma do?

Back

creates a pause to clarify the sentence.

Front

what is an introductory comma?

Back

use commas before and/or after words that are interjected into sentences.